Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 288 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the kind of juice (c) the ironing time (d) the same cotton bud
2. 2.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
3. 3.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if shaken (c) yes, if cooled (d) no, it stays brown
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we change it (c) we keep it the same
5. 5.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) cutting the lemon (d) writing the message
6. 6.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
7. 7.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
8. 8.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
9. 9.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
10. 10.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) ironing the paper (c) reading the message (d) cutting the lemon
11. 11.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False
12. 12.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
13. 13.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) it turned into air (c) the ink is magnetic (d) the paper ate it
14. 14.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
15. 15.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
16. 16.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) a balloon (d) an adult with an iron
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) a battery cell (d) white paper
18. 18.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) putting the iron away (d) writing the message
19. 19.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) physical (c) musical (d) magnetic
20. 20.🔍 Which is the odd one out? (a) plugging in the iron (b) reading the message (c) cutting the lemon (d) ironing the paper
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we measure it (c) we change it
22. 22.🍋 Which of these steps is a job a child can do? (a) writing the message (b) cutting the lemon (c) plugging in the iron (d) putting the iron away
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the same paper (c) the iron setting (d) how dark the writing is
24. 24.🔍 Which is the odd one out? (a) cutting the lemon (b) dipping the cotton bud (c) letting the paper dry (d) writing the message
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we measure it (c) we keep it the same
26. 26.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
27. 27.True or false: letting the paper dry is a job a child can do. (a) True (b) False
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) True (b) False
29. 29.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
30. 30.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) whoever is fastest (c) only an adult (d) the youngest child
31. 31.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) dipping the cotton bud (d) cutting the lemon
32. 32.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing turns green (d) writing stays faint
33. 33.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) paper turns lemony (c) the juice scorches first (d) heat adds colour
34. 34.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
35. 35.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) rub your eyes (d) wash your hands
36. 36.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
37. 37.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
38. 38.🔍 Which is the odd one out? (a) writing the message (b) putting the iron away (c) cutting the lemon (d) plugging in the iron
39. 39.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it can burn skin (d) it is magnetic
40. 40.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) plugging in the iron (c) ironing the paper (d) cutting the lemon

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